CN112255228A

CN112255228A - Online detection equipment for nitrogen oxides in air

Info

Publication number: CN112255228A
Application number: CN202011091136.XA
Authority: CN
Inventors: 杜亚举; 李保生; 张斌
Original assignee: Hefei Ftun Optoelectronics Technology Co ltd
Current assignee: Hefei Ftun Optoelectronics Technology Co ltd
Priority date: 2020-10-13
Filing date: 2020-10-13
Publication date: 2021-01-22

Abstract

The invention discloses online detection equipment for nitrogen oxides in air, which belongs to the technical field of atmospheric monitoring and comprises a shell and a detection assembly arranged in the shell, wherein the shell is divided into three areas from bottom to top through two mesh plates arranged in parallel, the middle area formed between the two mesh plates is a working chamber, the top area and the bottom area of each mesh plate are heat dissipation chambers, and the detection assembly is arranged in the working chamber; the detection assembly comprises a zero gas filter, an oxidation filter material cylinder for oxidizing NO into NO2, an ozone generator, a conversion furnace for converting NO2 into NO, a reaction chamber for reacting NO with ozone and a photomultiplier for acquiring a photoelectric signal of the reaction chamber, wherein the photomultiplier is in signal connection with a signal acquisition and processing unit, and the total concentration of nitrogen oxides, the concentration of NO and the concentration of NO2 are calculated through the photoelectric signal received by the signal acquisition and processing unit. The three-layer structure through the shell facilitates efficient heat dissipation of work of the detection assembly.

Description

Online detection equipment for nitrogen oxides in air

Technical Field

The invention relates to the technical field of atmospheric monitoring systems, in particular to online detection equipment for nitrogen oxides in air.

Background

The nitrogen oxide has great harm to the environment, is one of the main substances forming acid rain, is also one of the main substances forming photochemical smog in the atmosphere and is an important factor for consuming ozone, and the nitrogen oxide has light stimulation to eyes and upper respiratory tract mucosa, mainly invades bronchioles and alveoli in the deep part of the respiratory tract and causes harm to the health of human bodies. In view of the above-mentioned hazards of nitrogen oxides, it is necessary to measure nitrogen oxides, to know and understand the concentration of nitrogen oxides in the air, to evaluate the quality of the air, and to provide warning limits. The long-term monitoring can also revise or establish the accumulated data of national sanitation standards and other environmental protection regulations, and create conditions for forecasting.

At present most nitrogen oxide concentration detection all adopts the signal of telecommunication that the chemical reaction between NO and the ozone produced to measure each item nitrogen oxide concentration content in the sample gas, but current check out test set needs multinomial equipment cooperation to use, the structure is complicated, the difficult maintenance of breaking down is changed, and pile up each item equipment together and lead to the heat that work produced not to go out, in high temperature environment, photoelectric detection's the unable steady operation of instrument, the detection achievement for nitrogen oxide brings inconvenience, and traditional detection device calculates nitrogen oxide's concentration value through photoelectric signal, lack the reference signal and compare, lead to the testing result error to appear easily, thereby influence nitrogen oxide's measurement accuracy.

Disclosure of Invention

The invention aims to solve the problems that the traditional nitrogen oxide content detection device is poor in heat dissipation effect, complex in structure, difficult to replace due to faults and poor in measurement accuracy, and provides the online detection equipment for the nitrogen oxide in the air, which has the advantages of modular design, convenience in disassembly and replacement of parts, improved heat dissipation effect due to the three-layer structure of the shell and high measurement accuracy.

The invention achieves the purpose through the following technical scheme, and the online detection equipment for nitrogen oxides in air comprises a shell and a detection assembly arranged in the shell, wherein the shell is divided into three areas from bottom to top through two mesh plates which are arranged in parallel, the middle area formed between the two mesh plates is a working chamber, the top area and the bottom area of each mesh plate are heat dissipation chambers, and the detection assembly is arranged in the working chamber;

the detection assembly comprises a zero gas filter, an oxidation filter material cylinder for oxidizing NO into NO2, an ozone generator, a conversion furnace for converting NO2 into NO, a reaction chamber for reacting NO with ozone and a photomultiplier for acquiring a photoelectric signal of the reaction chamber, wherein the photomultiplier is in signal connection with a signal acquisition and processing unit, and the total concentration of nitrogen oxides, the concentration of NO and the concentration of NO2 are calculated through the photoelectric signal received by the signal acquisition and processing unit.

Preferably, all the heat dissipation fans are installed inside the heat dissipation chambers, heat dissipation baffles with heat dissipation holes are installed outside the heat dissipation chambers, the top heat dissipation chamber is an air inlet duct, the bottom heat dissipation chamber is an air outlet duct, and a heat dissipation air path is formed between the top heat dissipation chamber and the working chamber.

Preferably, the zero gas filter outlet end, the oxidation filter material cylinder outlet end and the converter inlet end are connected through a first three-way valve pipeline, and the converter outlet end, the first three-way valve outlet end and the reaction chamber inlet end are connected through a second three-way valve pipeline.

Preferably, an ozone purifier is further connected between the ozone generator and the gas inlet end of the reaction chamber through a pipeline, and an ozone absorber is connected to the gas outlet end of the reaction chamber through a pipeline.

Preferably, the pipe connection is detachably fixed by a connecting flange.

Preferably, the ozone generator comprises an air compressor, an air dryer and an ozone reactor which are connected in sequence through pipelines.

Preferably, the air inlet end of the air compressor is connected with an air production pipe, the air production pipe is connected with an air production head, the air production head is provided with air production holes facing to different directions, and the surfaces of the air production holes are paved with dust screens.

Preferably, a peltier cooling patch is mounted at the bottom of the photomultiplier tube, a cooling surface of the peltier cooling patch is attached to the photomultiplier tube, a hot surface is attached to the heat dissipation fin, and the heat dissipation fan is mounted on the heat dissipation fin.

Compared with the prior art, the invention has the beneficial effects that: the shell is of a three-layer structure, the detection assembly is arranged in the middle area of the shell, the top and the bottom of the shell cannot be sealed, and the heat dissipation fans of the top and the bottom heat dissipation chambers are used for heat dissipation, so that the heat dissipation effect is improved, and the detection assembly is not easy to damp; the detection assembly is formed by connecting pipelines of various electrical equipment, the single electrical equipment is convenient to disassemble and replace, the NO content in the sample gas is measured by photoelectric signals generated by the reaction of ozone and NO in the sample gas, the total content of nitrogen oxides in oxygen is measured by converting NO2 into photoelectric signals generated by the reaction of NO and ozone, and therefore the content of N02 in the total content of the nitrogen oxides is also measured, the total content of the nitrogen oxides and the content of NO and N02 can be directly measured by the device, the structure is simple, and the accuracy is high.

Drawings

FIG. 1 is a schematic view of the overall structure of the inspection apparatus of the present invention.

FIG. 2 is a schematic view of a heat dissipation chamber according to the present invention.

FIG. 3 is a schematic view of the structure of the ozone purifier of the present invention.

Fig. 4 is a schematic view of a gas production head according to the present invention.

FIG. 5 is a diagram of a system for connecting the electronic components of the inspection apparatus of the present invention.

FIG. 6 is a schematic view of a heat dissipation structure of a photomultiplier tube according to the present invention.

In the figure: 1. the device comprises a shell, 2, a mesh plate, 3, a zero gas filter, 4, an oxidation filter material cylinder, 5, an ozone generator, 6, a first three-way valve, 7, a converter, 8, a second three-way valve, 9, a reaction chamber, 10, a signal acquisition and processing unit, 11, a photomultiplier, 12, an ozone purifier, 13, an ozone absorber, 14, a working chamber, 15, a heat dissipation chamber, 16, a heat dissipation fan, 17, a heat dissipation baffle, 18, an air compressor, 19, a gas production pipe, 20, a gas production head, 21, an air dryer, 22, an ozone reactor, 23, a gas production hole, 24 and a dust screen.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1 and 2, an online detection device for nitrogen oxides in air comprises a housing 1 and a detection assembly installed inside the housing 1, the housing 1 is divided into three areas from bottom to top by two mesh plates 2 arranged in parallel, a middle area formed between the two mesh plates 2 is a working chamber 14, top and bottom areas of the mesh plates 2 are heat dissipation chambers 15, the detection assembly is installed inside the working chamber 14, the top and bottom are not in contact with the housing 1, the mesh plates 2 are used as the bottom and top of the working chamber 14 and are communicated with the heat dissipation chamber 15, so that the heat dissipation effect of the detection assembly is greatly improved, and the detection assembly is not easily affected with damp, a heat dissipation fan 16 is installed inside the heat dissipation chamber 15, a heat dissipation baffle 17 with heat dissipation holes is installed outside, the heat dissipation chamber 15 at the top is an air inlet duct, the heat dissipation chamber 15 at the bottom is an air outlet, a heat dissipation air path is formed with the working chamber 14, the air path enters from the top heat dissipation chamber 15 and passes through the detection assembly and is discharged from the bottom heat dissipation chamber 15, so that heat generated by the operation of the detection assembly is taken out of the shell 1, and the shell 1 adopts a structure that air enters from the upper part and exits from the lower part, so that dust is not easy to enter the shell 1 from a heat dissipation port, and the dustproof effect is also improved;

as shown in fig. 5, the detecting assembly includes a zero gas filter 3, an oxidation filter cylinder 4 for NO oxidation to NO2, an ozone generator 5, a converter 7 for N02 to N0, a reaction chamber 9 for NO to ozone reaction, and a photomultiplier 11 for collecting photoelectric signals of the reaction chamber 9, the photomultiplier 11 is in signal connection with a signal collecting and processing unit 10, the total concentration of nitrogen oxides, NO concentration, and NO2 concentration are calculated from the photoelectric signals received by the signal collecting and processing unit 10, the zero gas filter 3 is used to filter out impurities in air to make the sample gas more pure, when detecting the content of nitrogen oxides in the sample gas, the sample gas passing through the zero gas filter 3 is directly input into the reaction chamber 9, ozone prepared by the ozone generator 5 is also input into the reaction chamber 9, ozone is chemically reacted with NO in the sample gas to generate optical signals, which are collected by the photomultiplier 11 and input to the signal collecting and processing unit 10, as NO signal; the sample gas passing through the zero gas filter 3 is directly input into the converter 7, NO2 in the sample gas is converted into NO, the converted gas is input into the reaction chamber 9, ozone prepared by the ozone generator 5 is also input into the reaction chamber 9, the ozone and the NO in the sample gas are subjected to chemical reaction, and a generated optical signal is collected by the photomultiplier tube 11 and input into the signal collection and processing unit 10 to be used as a total signal; the sample gas passes through the oxidation filter material cylinder 4, NO in the sample gas is oxidized into NO2 and then is input into the reaction chamber 9, ozone prepared by the ozone generator 5 is also input into the reaction chamber 9, and the NO2 does not react with the ozone, so the signal acquisition and processing unit 10 acquires the signal of the photomultiplier tube 11 as a reference signal; when detecting the NO content in the sample gas, the signal acquisition and processing unit 10 may obtain the NO content value by subtracting the reference signal value from the NO signal value, obtain the total nitrogen oxide content value by subtracting the reference signal value from the total signal value when detecting the total nitrogen oxide content in the sample gas, and obtain the NO2 content value by subtracting the reference signal value from the total signal value and then subtracting the NO signal value when detecting the NO2 content in the sample gas.

The zero gas filter 3 is connected with the gas outlet end of the oxidation filter material cylinder 4 and the gas inlet end of the converter 7 through a first three-way valve 6, the converter 7 is connected with the gas outlet end of the first three-way valve 6 and the gas inlet end of the reaction chamber 9 through a second three-way valve 8, the two three-way valves are used for switching the flow direction of sample gas, different channels are selected according to the detection requirements, an ozone purifier 12 is further connected between the ozone generator 5 and the gas inlet end of the reaction chamber 9 through a pipeline, the gas outlet end of the reaction chamber 9 is connected with an ozone absorber 13 through a pipeline, the ozone purifier 12 is used for improving the purity of ozone and improving the reaction efficiency of the reaction chamber 9, the ozone absorber 13 is used for absorbing redundant unreacted ozone and preventing the environment from being polluted by the ozone, the pipeline connection is detachably fixed through a connecting flange, each pipeline is connected through a detachable fixing flange, the disassembly and the assembly of the single electric appliance are convenient.

As shown in fig. 3 and 4, the ozone generator 5 includes an air compressor 18, an air dryer 21 and an ozone reactor 22 which are connected in sequence by pipelines, the air compressor 18 compresses air and sends the air into the air dryer 21 for drying treatment, the dried air is input into the ozone reactor 22 for high-voltage electric shock to generate ozone and send the ozone to the reaction chamber 9, an air inlet end of the air compressor 18 is connected with an air production pipe 19, the air production pipe 19 is connected with an air production head 20, the air production head 20 is provided with air production holes 23 facing different directions, dust screens 24 are laid on the surfaces of the air production holes 23, the air inlet end of the air compressor 18 adopts the collection head 20 with multi-directional air intake to collect air, so that the air intake amount is increased, and the dust screens 24 can prevent dust from entering the air compressor 18, thereby protecting the air compressor 18 and prolonging the service life of the ozone generator 5.

As shown in fig. 6, the peltier cooling patch 25 is attached to the bottom of the photomultiplier tube 11, the cooling surface of the peltier cooling patch 25 is attached to the photomultiplier tube 11, the hot surface is attached to the heat dissipation fins 26, and the heat dissipation fan 27 is attached to the heat dissipation fins 26, so that the temperature of the converter 7 needs to be raised to 380 ℃, and the photomultiplier tube 11 needs to operate at a temperature of 0 ℃ or lower, and therefore, the operating temperature is detected by high-precision bridge temperature detection, the temperature of the photomultiplier tube 11 is lowered by the peltier cooling patch 25, the peltier cooling patch 25 is cooled by a semiconductor, the cold surface is attached to the photomultiplier tube 11, and the hot surface is taken away by the heat dissipation fan 27 in cooperation with the heat dissipation fins 26.

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.

Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.

Claims

1. The on-line detection equipment for nitrogen oxides in air comprises a shell (1) and a detection assembly arranged inside the shell (1), and is characterized in that the shell (1) is divided into three areas from bottom to top through two mesh plates (2) arranged in parallel, the middle area formed between the two mesh plates (2) is a working chamber (14), the top and bottom areas of the mesh plates (2) are heat dissipation chambers (15), and the detection assembly is arranged inside the working chamber (14);

the detection assembly comprises a zero gas filter (3), an oxidation filter material cylinder (4) for oxidizing NO into NO2, an ozone generator (5), a conversion furnace (7) for converting N02 into N0, a reaction chamber (9) for reacting NO with ozone and a photomultiplier (11) for collecting photoelectric signals of the reaction chamber (9), wherein the photomultiplier (11) is in signal connection with a signal collection processing unit (10), and the total concentration of nitrogen oxides, the concentration of NO and the concentration of NO2 are calculated through the photoelectric signals received by the signal collection processing unit (10).

2. The on-line detection equipment for nitrogen oxides in air as claimed in claim 1, wherein the inside of the heat dissipation chamber (15) is installed with a heat dissipation fan (16), the outside is installed with a heat dissipation baffle (17) with heat dissipation holes, the top heat dissipation chamber (15) is an air inlet duct, the bottom heat dissipation chamber (15) is an air outlet duct, and a heat dissipation air path is formed with the working chamber (14).

3. The on-line detection equipment for nitrogen oxides in air according to claim 2, wherein the outlet end of the zero gas filter (3), the outlet end of the oxidation filter material cylinder (4) and the inlet end of the converter (7) are connected through a first three-way valve (6) by pipelines, and the outlet end of the converter (7), the outlet end of the first three-way valve (6) and the inlet end of the reaction chamber (9) are connected through a second three-way valve (8) by pipelines.

4. The on-line detection equipment for nitrogen oxides in air according to claim 1, characterized in that an ozone purifier (12) is further connected between the ozone generator (5) and the inlet end of the reaction chamber (9) through a pipeline, and an ozone absorber (13) is connected to the outlet end of the reaction chamber (9) through a pipeline.

5. The on-line detection equipment for nitrogen oxides in air as claimed in claim 3 or 4, wherein the pipeline connection is detachably fixed through a connecting flange.

6. The on-line detection equipment for nitrogen oxides in air according to claim 1 or 4, characterized in that the ozone generator (5) comprises an air compressor (18), an air dryer (21) and an ozone reactor (22) which are connected in sequence through pipelines.

7. The on-line detection equipment for nitrogen oxides in air according to claim 6, characterized in that the air intake end of the air compressor (18) is connected with an air production pipe (19), the air production pipe (19) is connected with an air production head (20), the air production head (20) is provided with air production holes (23) facing different directions, and the surface of the air production hole (23) is paved with a dust screen (24).

8. The on-line detection equipment for nitrogen oxides in air as claimed in claim 1, wherein a peltier cooling patch (25) is mounted at the bottom of the photomultiplier tube (11), the cooling surface of the peltier cooling patch (25) is attached to the photomultiplier tube (11), the hot surface is attached to the heat dissipation fins (26), and the heat dissipation fins (26) are provided with heat dissipation fans (27).